OXYGENATED TETRAPYRROLES PRODUCED FROM PORPHYRINOGENS

Oxygenated tetrapyrroles are produced in small quantities, typically less than 2%, when porphyrinogens are allowed to reoxidize in the air exposed to even dim light. Oxygen inserts into carbon-carbon double bonds and carbon-hydrogen single bonds to give rise to chlorins and porphyrins with hydroxy groups. These compounds can also undergo spontaneous additional reactions including further oxidation to carbonyls and dehydration to form carbon-carbon doublebonds. Derivatives of uroporphyrin, coproporphyrin, and other common tetrapyrroles have been isolated and fully characterized to elucidate their structure. Although the quantities formed are small, a surprising array of novel compounds is formed. (C) 1994 Academic Press, Inc.